02447nas a2200217   4500000000100000000000100001008004100002260001500043100002100058700002100079700002600100700001800126700002000144700001900164245010200183856007000285300001200355490000700367520184100374022001402215       2022                            d  c2022-01-181 aJohannes Dornhof1 aJochen Kieninger1 aHarshini Muralidharan1 aJochen Maurer1 aGerald A. Urban1 aAndreas Weltin00aMicrofluidic organ-on-chip system for multi-analyte monitoring of metabolites in 3D cell cultures  uhttps://pubs.rsc.org/en/content/articlelanding/2022/lc/d1lc00689d  a225-2390 v223 aThree-dimensional cell cultures using patient-derived stem cells are essential in vitro models for a more efficient and individualized cancer therapy. Currently, culture conditions and metabolite concentrations, especially hypoxia, are often not accessible continuously and in situ within microphysiological systems. However, understanding and standardizing the cellular microenvironment are the key to successful in vitro models. We developed a microfluidic organ-on-chip platform for matrix-based, heterogeneous 3D cultures with fully integrated electrochemical chemo- and biosensor arrays for the energy metabolites oxygen, lactate, and glucose. Advanced microstructures allow straightforward cell matrix integration with standard laboratory equipment, compartmentalization, and microfluidic access. Single, patient-derived, triple-negative breast cancer stem cells develop into tumour organoids in a heterogeneous spheroid culture on-chip. Our system allows unprecedented control of culture conditions, including hypoxia, and simultaneous verification by integrated sensors. Beyond previous works, our results demonstrate precise and reproducible on-chip multi-analyte metabolite monitoring under dynamic conditions from a matrix-based culture over more than one week. Responses to alterations in culture conditions and cancer drug exposure, such as metabolite consumption and production rates, could be accessed quantitatively and in real-time, in contrast to endpoint analyses. Our approach highlights the importance of continuous, in situ metabolite monitoring in 3D cell cultures regarding the standardization and control of culture conditions, and drug screening in cancer research. Overall, the results underline the potential of microsensors in organ-on-chip systems for successful application, e.g. in personalized medicine.  a1473-0189